Answer:
total distance travel by them to cross river is 17.3 m
Step-by-step explanation:
Assume A be the initial position of both person and B as apposite point to A
u component of velocity along SOUTH DIRECTION is 4 cos30 = 0.4330 m/s
v component of velocity along SOUTH DIRECTION is 4 cos90 = 0 m/s
total speed will be = 0.4330 + 0 = 0.4330 m/s
time taken
time taken 
component of u in downstream direction = 4 cos120 = -0.25 m/s
component of v in downstream direction = 4 cos 0 = 0.5 m/s
total component in downstream will be -0.25 + 0.5 = 0.25
total distance travel by them to cross river is
downstream.
Whether it can be equal to that value. For example, if 5 is greater than x, then an open circle will be useful. If 5 is greater than or equal to x, a closed circle will be used.
When two fractions have the same numerators, the one with the smaller denominator is the greater fraction.

So Kelvin is right.
Yes because -5/4 = -1 1/4 as soon does 5/-4